FAQ’s: Oil

Your symptoms are very consistent with a failure of the diaphragm in your mechanical fuel pump. The fuel that is normally contained above the diaphragm is likely leaking through the diaphragm and draining in through a drain hole in the block, under the mounting flange of the pump. I would not use the engine until you remove the pump and replace the diaphragm. – Updated: May 26, 2004

We prefer straight 30 weight detergent oil in the Atomic 4, simply because the engines are usually used at a constant power setting, and mostly during the warm part of the year (which doesn’t really require a multi-viscosity oil). Later Universal owner’s manuals did list multi-viscosity oils as a suitable substitute to straight viscosity oils, but we can’t find where they ever recommended over a 10-30 weight.

The downside to using heavier than recommended oil is that (while the pressure might be reassuringly high on the gauge in the cockpit), the head loss in oil pressure between the port where it enters each bearing in the center, to the outside of the bearing, is much greater as oil thickness increases. This means that the outer edges of each bearing (crankshaft and cam) is getting somewhat less than designed oil pressure. – Updated: May 26, 2004

You can indeed install a “T” fitting and an oil pressure safety switch along with your original oil pressure sending unit, all into the pressure port just behind the flywheel housing (ahead of the flame arrestor). The switch shown in our online catalog is a normally open switch that closes above10 psi.

In addition to your original “oil pressure gauge sending unit” and this “oil pressure safety switch” to shut off your electric fuel pump when the engine is not running, there is a third unit that you might consider. This would be the “oil pressure warning switch” that is used in our temperature and oil pressure warning system (product number: KTAS_01_191). This switch is a normally closed switch which closes below approximately 10 psi (just the opposite of the switch used in the electric fuel pump circuit) to alert you to low oil pressure.

In my judgment, if all three of these switches are to be used, their combined weight (plus two “T” fittings) gets a bit heavy to all hang on the1/8″ pipe nipple behind the flywheel housing. If this is your plan, I would recommend our oil safety switch kit, which includes the safety switch itself, a bracket, hose, and all the fittings necessary to mount the switch (and your original oil pressure sending unit) on a nearby bulkhead.

You can then install the pressure switch from the warning system and a “T” (which is included in that kit) into the pressure port in the engine. The hose from your bulkhead mounted safety switch kit will then install into the third leg of that “T” fitting, instead of directly into the engine, leaving only the weight of the (rather light) warning switch hanging on the 1/8″ pipe nipple threaded into the block. – Updated: January 6, 2004

Assuming that you have been using detergent oil, which is normal for the Atomic 4, the detergent will emulsify (causing suds – like laundry detergent) if even a small amount of water enters the crankcase. The emulsifying process almost always creates the impression that there is more water in the oil than is usually the case.

Whenever water does make it into the oil pan, particularly in small amounts, we always recommend changing the oil at least two or three times, or until all evidence of the water is removed. If the water can be removed in this fashion and not return, we recommend that you observe the oil for at least 10 or 20 hours of operation before doing anything more serious. Each year, we hear of water intrusion into the crankcase which never re-occurs after it is removed through changing the oil multiple times.

The most common way that water gets into the crankcase is from engine cooling water backing up within the exhaust system until it floods back through the exhaust manifold. It then passes into, and through, the combustion chambers, and down to the oil pan. This scenario can be caused by simply over-cranking a hard starting engine (with the raw water through-hull open) or from an internal failure of the water lift muffler.

Sometimes, problems within the exhaust system will only manifest after sailing. If water intrusion only occurs after sailing, try closing the raw water thru-hull fitting while sailing, and see if the problem goes away. If it does, you’ll have to troubleshoot the exhaust system, or keep your thru-hull closed whenever you’re sailing.

In a few cases, leaky head gaskets can result in a small amount of water getting into the oil. When head gaskets fail, there is usually evidence of poor running or hard starting caused by loss of compression and/or water fouling the spark plugs.

Exhaust system problems and head gasket failures have one important feature in common: It’s practically impossible for either exhausted cooling water or water from head gasket failures to enter the crankcase without first passing through the combustion chambers. Therefore, both of these sources of water intrusion would logically result in poor running, or some other obvious evidence of water being in the combustion chambers.

In rare cases, both Sherwood and Jabsco water pumps have the potential of passing a bit of water into the crankcase if their water seal leaks and the weep holes in their housings become plugged with grease or other crud. In this scenario, trapped water along the shaft of the pump can force past the second seal (the one preventing oil from coming out of the crankcase) and into the oil pan. Oberdorfer pumps have large weep holes in their housings and don’t really have this same potential.

If there is no indication of water getting in through the combustion chambers or any other way externally, a crack is usually indicated. If you do suspect a crack in one of your water jackets, you can pinch off the water discharge hose coming off the back of the manifold for several 10 second pressure checks. A flexible impeller pump in good condition can produce 20 PSI when deadheaded in this fashion. If there is a crack anywhere in the water-jacketed castings, this amount of pressure will force water into the oil pan at a rate that should be unmistakable.

If you can confirm that water is indeed entering your oil pan through a defective casting, you’ll have to remove the engine for disassembly and repair. Cracks in the floor of the cooling water jacket in the block are frequently repairable once the engine is disassembled for $200 to $400, depending on the length of the crack. – Updated: January 6, 2004

Most oil leaks occur along the carburetor side of the engine. Starting at the flywheel end of the engine and working rearward, leaks could be from the oil sending unit directly behind the flywheel housing (or from its connecting fittings), from under the valve cover, from between the block and fuel pump, or from around the oil pressure regulating valve.

If the leak seems to be from the rear of the engine, the rear seal around the output coupling could be leaking. However, almost all leaks from along the carburetor side of the engine usually run back along the upper ledge of the oil pan and end up dripping off the aft end of the engine. Therefore, to be certain that the rear oil seal is really leaking, it is necessary to thoroughly clean the rear end of the oil pan so that the oil can actually be seen to run down from the seal.

On the starter side of the engine, leaks are usually limited to the area of the water pump, with the shaft seal of the pump (the seal toward the engine) usually causing the leak.

If the leak is clearly coming from the front of the engine, it could be that the return holes in the flywheel housing below the air seal (or “slinger seal”) around the front of the crankshaft are clogged. When these holes are clogged, oil being flung outward by the tapered collar around the front of the crankshaft cannot drain back into the crankcase, and it is running (instead) down behind the flywheel, along the front face of the flywheel housing, and out through a drain hole in the bottom of the same housing. – Updated: December 31, 2003

The smell of gasoline in oil is almost certainly caused by a small leak in the diaphragm of the mechanical fuel pump. This condition can be quite serious. In worst cases, fumes can collect to the point that they can ignite within the crankcase. Historically, the worst damage we have ever had reported (in this case, a second-hand report) was a flywheel cover being blown from the front of the engine (although the engine itself kept right on running!).

What happens is that a small pinhole develops within the diaphragm, which allows fuel to pass into the bottom of the pump housing and into the crankcase through a small oiling hole in the block. The danger is that the pump can still usually keep up with the demands of supplying fuel to the carburetor, which means that these small leaks might go undetected for rather long periods of time.

Other indications of leaky diaphragms include blackening and/or thinning of the oil, and eventually a rising of the oil level within the crankcase. – Updated: November 9, 2003

Unfortunately, the Catalina 30 is one of the most unforgiving boats in the fleet for backing up sea water in through the exhaust system.

There is nothing you can really do to improve on the boat’s inherent tendency to back up water during cranking. It’s simply a matter of very little storage capacity in the water lift muffler and associated exhaust piping (due largely to the center cabin location of the engine). All you can do is remember to close the thru-hull anytime that the engine is a bit reluctant to start, and also during sailing. It’s really a good idea to close thru-hulls on most boats while sailing, if only as a precaution against a random failure within the exhaust system.

In addition to the over-cranking issue, you should check to be sure that the siphon break in the 1/2″ cooling water hose between the aft end of the manifold and the inlet to the exhaust system just above the water lift muffler is working. This hose curves up and under the galley sink, and the siphon break is that small brass check valve at the top of that loop. You should be able to blow down through this little valve. If it is clogged, you are in danger of siphoning water in through the engine, and into the exhaust system while the engine is sitting between uses, if you forget to close the thru-hull. – Updated: November 4, 2003

As our technical service reaches more and more Atomic 4 owners, I suppose it’s logical that we would eventually run into a few of the “leftover” issues that bothered tech service folks at Universal in their later years. Erratic oil pressure in late model engines was one such festering issue in the late 1980’s, and it continues to show up on our plates today as well.

There are, of course, the few cases of loose electrical connections (or short circuits) between the sending units and gauges, but for the most part, indications on gauges have been real, and the late model spring and ball type of regulating valve has been the culprit.

Problems in late model regulating valves almost always relate to the fact that the spring-loaded ball doesn’t always seat squarely over the orifice in the block, through which oil is being supplied by the pump. It’s interesting to note that Universal tried several different sizes of balls during their later years, in an apparent attempt to steady out the regulating valves; however, it is not at all clear that either of the two sizes they tried made any significant improvement in the function of the valve.

In many cases, as the threaded part of the valve is turned in (clockwise) to increase oil pressure, the spring arches slightly so as to press against the side of the ball. This side load causes the ball to move more to one side of the orifice which allows more oil to pass through, instead of less. This is how you might get a slight decrease in pressure, while turning the adjustment in, in an attempt to increase oil pressure.

Other symptoms of regulating valve problems include oil pressure decreasing as RPM increases (another manifestation of the ball moving off center) and low oil pressure which doesn’t respond normally as the adjusting bolt is turned in. This problem is sometimes caused by a regulating spring that has worn thin by rubbing along the inside of the threaded hole into which the adjusting bolt is installed.

I’m not sure that we would ever have come to this conclusion on our own, but one of the good Universal technical service folks put a bug in our ear back in the mid 1980’s to the effect that early model regulating valves, which were built around a spring-loaded pointed shaft instead of a spring loaded ball, tended to provide much more consistent control.

In the event that you might be facing oil pressure issues that do not respond to normal adjustment (35 to 40 psi fully warmed up at normal cruise, and 20 psi or so at idle), you might want to consider the REGULATING VALVE found in the overhaul section of our online catalog before taking on any heavier maintenance on your engine. Many overhauls have been headed off by the installation of this “early model” style of valve.

Another significant aspect to the problem of regulation relates to the fact that the orifice in the block is not always perfectly centered with the centerline of the threaded shaft.

The effect of this misalignment sometimes causes oil pressure to take a nose dive during an adjustment, as the threaded shaft nears the end of its travel and forces the ball (or even the pointed shaft of early model valves) off to the side of the orifice in the block. In these cases, it’s usually necessary to use the REGULATING VALVE SEAT DRESSING TOOL shown in the specialty tools section of our online catalog to bevel the orifice slightly, bringing it into alignment with the shaft or ball.

To summarize the issue of oil pressure regulation, since we’ve been dressing all the orifices of the oil pressure regulating valve in the block and using early style regulating valves during our rebuilding operation, we have essentially eliminated the hassle we used to face in getting oil pressure to settle down during test runs. – Updated: November 4, 2003

Early Universal manuals recommended oil pressures between 35 and 40 PSI. Our own manual recommends 40 PSI (fully warmed up) at your favorite cruise setting, and our oil pressure troubleshooting section suggests readjusting the pressure if it drops below 35 PSI at normal cruise.

In terms of idle pressure, Universal manuals allowed pressures as low as 10 PSI (fully warmed up), while our own manual is somewhat more conservative, suggesting that pressure at idle should be no lower than 1/2 of the pressure at normal cruise (17 to 18 PSI).

It is very important to clarify two issues regarding oil pressure: 1) The intent of all the above recommendations is to provide a range of oil pressures below which you should attempt to readjust the pressure by adjusting the regulating valve, not necessarily to establish a threshold below which you would have to pull the engine for overhaul. 2) It is our understanding that the recommended oil pressures shown in the original factory manuals (and certainly in our own manual) were intended to apply all the way to the rated maximum (theoretical) output of 30 horsepower at 3500 RPM.

These two issues prompt an important secondary question: What is a reasonable minimum (continuous duty) oil pressure when operating below maximum rated power and RPM? We are told by several different sets of experts (engineers and race car drivers) that they use 10 PSI per 1000 RPM as a minimum oil pressure for continuous duty operation. For example, at 3500 RPM, minimum continuous duty oil pressure would be 35 PSI. As a point of reference, specifications relating to continuous duty operation mean that if the specifications are violated, the engine won’t self-destruct within the next 5 minutes, but it does mean that its life expectancy will be significantly reduced.

While this rule of thumb equates rather well to the factory recommendation of 35 PSI at 3500 RPM, the same 35 PSI seems somewhat conservative if your favorite cruising power setting is down around 2000 RPM, where you could (by these experts’ rule of thumb) look at 20 PSI as your lowest pressure for continuous duty.

In summary: We recommend that you try, to the extent possible, to adjust your oil pressure to maintain a minimum of 35 PSI at your normal cruising power setting (whatever that setting might be). If you cannot maintain an oil pressure of at least 10 PSI per 1000 RPM, we recommend that you consider serious corrective action, including pulling the engine for overhaul, particularly if you are contemplating using the boat for anything other than pulling in and out of your slip. – Updated: November 4, 2003

The earliest Universal Operation and Maintenance Manual contains a note that discourages the use of detergent oil when breaking in a brand new engine. All other subsequent Universal Owner’s manuals recommend the use of S.A.E. 30 weight, detergent oil down to 32 degrees. 10 – 30 multiviscosity oil is also acceptable.

We have heard a few good reports from customers who have tried some of the modern low-friction synthetic oils, but we have done no research or testing of our own on any special oils. We believe that any good quality straight viscosity 30 weight oil is more than adequate for insuring a long life in our engines. Before any special oil is used, make certain that there are no manufacturer warnings on the can regarding the use of the oil in engines with built in clutch mechanisms (like our reversing gears). It is our understanding that the Slick 50 brand (for example) has such a warning.

In terms of capacity, when the engine is level and completely empty (as after an overhaul), it will take about 5 1/2 quarts to fill it. Given the rearward slant that most engines have after installation, and the fact that it is impossible to get all the oil out during an oil change, you will seldom need to add more than three or three and a half quarts of oil to refill the engine.

In all cases, the oil level in the crankcase should be maintained at the full mark on late model dipsticks, or to the upper mark on early model dipsticks (which is exactly the same level). The late model dipsticks are considerably easier to use and are interchangeable with the sticks on early model engines. – Updated: November 4, 2003

There is probably no stronger consensus among the entire Atomic 4 fraternity (present and past), as well as among the few retired Universal folks who are good enough to take questions from us on occasion, than that which exists on the great value of Marvel Mystery Oil added to the gasoline. This fine old product is available at practically any auto parts store, and it is the only additive we recommend be used in the gasoline or crankcase.

The recipe on the can calls for 4 ounces per 10 gallons to be added to the gasoline, but the experts at Universal recommended that we at least double that amount if you even suspect that you may be having sticky valves. The main properties of the oil are that it is thin, highly penetrative and, as per the can, “it leaves behind a lubricating residue when introduced into the combustion process.” What it does is to keep the valves free in their guides and rings free in their grooves. It also tends (through its lubricating residue) to cushion the valves somewhat in the way that lead additives used to do.

If you are already experiencing sticky valves and rings, you can introduce several squirts of Mystery Oil from an oil can directly into the cylinders through the spark plug holes.

If you have reason to believe that your oil rings are a bit sticky (e.g.,higher than normal oil consumption), you can add up to a quart in the crankcase during oil change. – Updated: November 4, 2003

The most logical explanation of an oil leak in the area of the water pump (presumably dripping from under the pump) is that the oil seal in the flange of the pump is leaking. – Updated: November 4, 2003

There are only three sources for a continuing oil leak appearing below the flywheel housing: (listed somewhat in order of likelihood)

1) Overfilling the crank case. There is no conventional seal in front of the crankshaft, and if the crankcase is overfilled by much more than a quart or so, some oil can splash out of the front of the engine, just behind the flywheel, especially when sailing in choppy water.

2) A leaky gasket between the flywheel housing and the front of the block. Such a leak would be very unusual except possibly immediately after an overhaul.

3) Clogged drain holes in the “slinger seal” in front of the crankshaft.

The slinger seal consists of a collar machined around the front of the crankshaft where it extends out through the flywheel housing, just behind the flywheel. The outside edge of this collar is sharpened to a dull edge which lines up with the inside diameter of the hole in the flywheel housing. When oil tries to leave the crankcase, it encounters the crankcase side of this collar, and gets “slung” outward (hence the the name “slinger seal”) into a groove cut into the inside diameter of the hole in the flywheel housing.

There are small drain holes (approximately 5) in the bottom of the groove around the inside of the hole in the flywheel housing, which allows the oil to flow back into the crankcase after it is flung outward into the groove by the edge of the sharpened collar on the crankshaft.

Every now and then, those holes get clogged with crud and oil cannot flow back into the crankcase as fast as it is being flung out by the slinging collar. – Updated: November 4, 2003